The West is getting dustier, says CU-Boulder study

The amount of dust being blown across the landscape has increased over the last 17 years in large swaths of the West, according to a new study led by the University of Colorado Boulder.

The escalation in dust emissions — which may be due to the interplay of several factors, including increased windstorm frequency, drought cycles and changing land-use patterns — has implications both for the areas where the dust is first picked up by the winds and for the places where the dust is put back down.

“Dust storms cause a large-scale reorganization of nutrients on the surface of the Earth,” said Janice Brahney, who led the study as a CU-Boulder doctoral student. “And we don’t routinely monitor dust in most places, which means we don’t have a good handle on how the material is moving, when it’s moving and where it’s going.”

Based on anecdotal evidence, such as incidents of dust coating the snowpack in the southern Rockies and a seemingly greater number of dust storms noticed by Western residents, scientists have suspected that dust emissions were increasing. But because dust has not been routinely measured over long periods of time, it was difficult to say for sure.

“What we know is that there are a lot of dust storms, and if you ask people on the Western Slope of Colorado, or in Utah or Arizona, you’ll often hear them say, ‘Yeah, I grew up in this area, and I don’t remember it ever being like this before,’ ” said CU-Boulder geological sciences Associate Professor Jason Neff, Brahney’s adviser and a co-author of the paper. “So there is anecdotal evidence out there that things are changing, but no scientific data that can tell us whether or not that’s true, at least for the recent past.”

For the new study, recently published online in the journal Aeolian Research, the research team set out to determine if they could use calcium deposition as a proxy for dust measurements. Calcium can make its way into the atmosphere — before falling back to earth along with precipitation — through a number of avenues, including coal-fired power plants, forest fires, ocean spray and, key to this study, wind erosion of soils.

The amount of calcium dissolved in precipitation has long been measured by the National Atmospheric Deposition Program, or NADP, which first began recording the chemicals dissolved in precipitation in the late 1970s to better understand the phenomena of acid rain.

Brahney and her colleagues reviewed calcium deposition data from 175 NADP sites across the United States between 1994 and 2010, and they found that calcium deposition had increased at 116 of them. The sites with the greatest increases were clustered in the Northwest, the Midwest and the Intermountain West, with Colorado, Wyoming and Utah seeing especially large increases.